Re: Recalculating OldestXmin in a long-running vacuum

Heikki Linnakangas wrote:

> I ran two 24h test runs with DBT-2, one with the patch and one without.
> To get comparable, predictable results, I turned autovacuum off and run
> a manual vacuum in a loop on the stock-table alone.
>
> As expected, the steady-state of the stock table is smaller with the
> patch. But only by ~2%, that's slightly less than I expected.
>
> But what surprises me is that response times went up a with the patch. I
> don't know why.

Maybe because of increased contention of ProcArrayLock?  (I assume you
are using that, althought I haven't seen the patch)

--
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.